• The Korean Journal of Physiology
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• 제29권2호
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• pp.217-223
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• 1995

Adenosine 5'-tetraphosphate (ATPP) was identified and quantified in extracts of rabbit platelets by elution of extracts containing authentic adenosine 5'-tetraphosphate and comparison of retention time with nucleotide standards using high-performance liquid chromatography technique. The amount of adenosine 5'-tetraphosphate was $0.62\;nmoles/10^{9}$ cells which was 62-fold lower than that of ATP but only 10-fold lower than that of ADP. During platelet aggregation induced by thrombin, adenosine 5'-tetraphosphate was released to a relatively high extent. The degradation rates and halflives of adenosine 5'-tetraphosphate were measured during incubation of platelets in whole blood, erythrocyte suspension and plasma, respectively. The results suggest that plasma contributes more than blood cells to the catabolism of adenosine 5'-tetraphosphate. The pattern of degradation indicates that ATPP may be degraded mainly to AMP by soluble enzymes in plasma and very slowly to ADP and/or AMP by ectoenzymes on blood cells such as erythrocyte. The nature of the enzymes responsible fer the degradation of adenosine 5'-tetraphosphate is yet to be identified.